Periodically change your AC or cabin air filter. Most cars and trucks within the last ten years have an AC or pollen filter to handle air going into the car’s cabin. If this filter is dirty:

Less air moves into the car.

Lower airflow than planned makes your AC system work harder.

Permits more pollutants into the passenger cabin.

Car makers generally recommend replacing the filter once a year but we generally visually examine the filter with you.

Periodically have your AC system serviced (not just “checked”) as preventative maintenance.

Your car loses refrigerant as a natural process, primarily through various joints.

Newer cars (within 10-15 years) are “critical charge” systems. They use less refrigerant and are less tolerant of variations in charge, high or low. So the loss of just a few ounces of refrigerant can shorten the life of the system, particularly the compressor. This may be the case even though your AC system continues to blow cold. Replacing your AC system is an expensive process, make it last as long as you can.

The only way to check the refrigerant level on newer vehicles is to do an “evacuate and recharge” process. This can take an hour and is generally not done for free.

The organization (MACS) designated by the EPA to certify AC technicians recommends this service be done annually. This strikes me as very often and I personally tend to recommend less often than that.